1 year later, Boston remembers the marathon bombing

BOSTON, MA - APRIL 14: Runner's shoes are laid out in a display titled, "Dear Boston: Messages from the Marathon Memorial" in the Boston Public Library to commemorate the 2013 Boston Maraton bombings, on April 14, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Andrew Burton/Getty Images)